UV curable composition, and UV curable sheet using same

Abstract

Provided are a UV curable composition which can be cured without undergoing a high-temperature heating step and has excellent adhesiveness and mechanical strength; and a sheet using the same. This UV curable composition includes a rubber component having a diene skeleton, a photopolymerization initiator, and a cross-linking agent, wherein the rubber component having a diene skeleton contains a solid rubber component and a liquid rubber component at 25° C. The UV curable composition can be cured by UV irradiation in a short time, and can thus be applied to not only an adherend having high heat resistance but also a wide range of members.

What is claimed is: 
     
       1. A UV curable sheet comprising an adhesive layer, which is formed from a UV curable adhesive composition comprising
 a rubber component with a diene skeleton, a photopolymerization initiator and a crosslinker, 
 wherein the rubber component with the diene skeleton comprises a solid rubber component and a liquid rubber component at 25° C., 
 the liquid rubber component contains a modified styrene-butadiene rubber, the modified styrene-butadiene rubber is a rubber modified with at least one selected from the group consisting of a carboxy group and an acid anhydride group, and 
 the crosslinker is a multi-functional (meth)acrylate, 
 
       wherein when a thickness of the sheet is 100 μm, a 90-degree peel strength based on JISK-6854 after irradiation of UV with a cumulative light amount of 1600 mJ/cm 2  through a high-pressure mercury lamp at room temperature is 10 N/inch or more. 
     
     
       2. The UV curable sheet according to  claim 1 , wherein a blending amount of the liquid rubber is 3-50 mass % relative to a total amount of the rubber component. 
     
     
       3. The UV curable sheet according to  claim 1 , wherein the solid rubber component comprises at least one selected from a butadiene rubber and a styrene-butadiene rubber. 
     
     
       4. The UV curable sheet according to  claim 1 , wherein a thickness of the adhesive layer is 5-200 μm. 
     
     
       5. A cured product of the UV curable sheet according to  claim 1 . 
     
     
       6. The UV curable sheet according to  claim 1 , wherein when a thickness of the sheet is 25 μm-50 μm, a tensile strength at cutting based on JISK-6251 after irradiation of UV with a cumulative light amount is 1600 mJ/cm 2  through a high-pressure mercury lamp at room temperature is 3.5 MPa or more. 
     
     
       7. A cured product of the UV curable sheet according to  claim 4 . 
     
     
       8. The cured product according to  claim 5 , wherein a gel fraction of the cured product is 50% or more. 
     
     
       9. The UV curable sheet according to  claim 1 , wherein the crosslinker is a multi-functional (meth)acrylate having 2 or more and 15 or less ethylenically unsaturated groups. 
     
     
       10. The UV curable sheet according to  claim 1 , wherein a blending amount of the liquid rubber is 10 mass % or more relative to a total amount of the rubber component.